1. Technical Field
The present disclosure relates to vehicle exterior environment recognition devices that recognize environment outside a vehicle. More specifically, the present disclosure relates to a vehicle exterior environment recognition device that identities a traffic light to be used as a control input of the vehicle.
2. Related Art
There are conventionally known a technique, such as collision avoidance control, which detects specific objects including another vehicle and a traffic light located ahead of a vehicle and avoid a collision with the leading, and a technique, such as a cruise control, which recognizes the color of the traffic light and controls to maintain a distance between own vehicle and a leading vehicle at a safe distance (for instance, see Japanese Patent No. 3,349,060).
Such a specific object is extracted from an image obtained by imaging an environment outside and ahead of the vehicle, based on the luminance and a distance data. For instance, Japanese Unexamined Patent Application Publication (JP-A) No. 2010-224925 discloses a technique to capture a color image outside the vehicle, group adjacent pixels, and recognize a light source, such as the traffic light, based on the distance, size, height, and a position of a grouped pixel with respect to a course of the vehicle.
The technique disclosed in JP-A No. 2010-224925 described above grasps the course of the vehicle from a lane line on a road surface based on a horizontal geometric model of the road surface in a real space, and determines a traffic light which exists on the course of the vehicle to be a traffic light for the vehicle. However, in an actual vehicle external environment, since the traffic light is recognized by various location patterns depending on the position of the traffic light, and the position and direction of the vehicle, the traffic light for the vehicle does not always exist on the course of the vehicle. Thus, in the technique disclosed in JP-A No. 2010-224925, an accuracy of identifying the traffic light for the vehicle cannot be improved.